Improvement in expanding rock-drills for shaft-boring apparatus



H. SONTAG.

Expanding Rock-Drills for Shaft-Boring Apparatus.

No. 134,943. Patentedjan.14.18 73.

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UNITED STATES PATENT OFFroE;

HUGO SONTAG, OF ST. LOUIS, MISSOURI.

IMPROVEMENT IN EXPANDING ROCK-DRILLS FOR SHAFT-BORING APPARATUS.

Specification forming part of Letters Patent No. [34,943, dated January 14, 1873.

To all whom it may concern:

Be it known that I, HUGO SONTAG, of the city and county of St. Louis and State of Missouri, have invented certain Improvements in Expanding Rock-Drills for Shaft-Boring Apparatus, of which the following is aspecification:

My invention consists in the-employment of a bit sliding horizontally in combination with a spring, the motion of which is limited by a set-screw, by means of which the sliding bit is forced out by the spring, and allowed also a backward mox ement to prevent any possibility of jamming.

Figure 1 is a side view of the bit, showing the spring-bit in its retracted position. Fig. 2 is a side View, showing the spring-bit in its forward position. Fig. 3 is an inside and Fig. 4 an outside View of the bit. Fig. 5 is a section at the line x m, Fig. 1.

Fig. 1 is a drill-bit similar to that shown in my application for patent on or about the 15th day of January, 1872, except that with the said bit K is associated a horizontally-sliding bit, L, arranged to cut the outer circumference of the enlarged bore. This spring-bit has a downwardly-curved end or cutter, M, and a shank, N sliding in suitable guide-grooves of the bit K. The two parts of the shank are connected by a cross-bar, 0, against which bears a spring, P, in such manner as to force the bit outward, but yet to allow its inward movement to prevent its becoming jammed fast against the side of the shaft-bore. R is a set-screw by which the outward movement of the radially-sliding bit L is limited. This bit may have a play of one inch, more or less, according to the character of the earth or rock through which the shaft is being sunk.

Claim.

unto set my hand.

HUGO SON TAG. Witnessese SAML. KNIGHT, STEPH. BERNARD. 

